speedfrk

go figure- Indeed.

DCXdynodog

WTF are you talking about?

DCXdynodog

Hmmm... My lawn mower is a commercial walk behind 48" deck with 3 blades. NONE of the blades have a key, just a large bolt (no lock washers either) and I've cut my lawn for 12 years just fine thank you!

I guess the key really has nothing to do with it.

rotflmao

Lynn

Wow, peas, green beans, bell peppers, lettuce, okra and most other "vegetables" are really fruits, and seedless grapes are vegetables.

Bananas do not have seeds. The black specks in the banana are the immature, unfertile beginnings of seeds.

Lynn

I'm a Benz owner, by God. I don't own a lawn mower, I employ someone who does.

mdp c230k

Amen, bother!

Seeds do not a fruit make.

levelr123g

yea well still waiting for the EXPERTS to dispute the documents i supplied, i guess that will never happen because it is hard to dispute fact.

Matt230K

I think we're all more interested in the dispute between fruits and vegetables. We need some documents for that.

mctwin2kman

Ok how about in this application both the key and the bolt torqued properly are needed. When you torgue the bolt to the right amount it will press itself onto the shaft and against the key. When the bolt is not torqued properly then the pulley must not be pressed over the key enough to keep the pulley spinning with the crank shaft. Allowing some slippage if you will. No that should not really happen but it is entirely posibble considering the amount of force present on the crank shaft. Now this being two disimiliar metals of course makes it far worse. The steel pulley matted to a steel shaft will expand and contract at the same rates therefore not leaving any room around the key to shear it like happened. Now with aluminum we have to diferent rates of expansion and contraction between the metals. Allowing the aluminum to expand more rapidly and create a gap between the key and the pulley and then of course the key will shear because the is no longer a tight fit between the key, the crank, and the pulley.

dswildfire

see? exactly.

all the more to mess with minds of children......and my own of course.

levelr123g

so back to the original statement, the key is needed to transmit torque from the crank to the pulley.

dswildfire

what's this key that we're talking about?

mdp c230k

This is not a proven fact on our engines. The fact remains that the sheared key might be the result of not enough torque on the bolt allowing the force to be placed on the alignment pin shearing it. Proper clamping torque of the bolt might hold the pulley in position all by itself. There is also the point of aluminum against steel, the soft aluminum will not have the ability to hold under the forces while a steel pulley would have no problem. The mu of Al is much less than that of steel. At any rate, some will believe and some won't.

speedfrk

Actually, the case I referred to was a stock factory pulley. So it was steel/steel. Aluminum is a worse case for a lot of reason including the softer material, expansion rate, etc.

"some will believe and some won't"

amen to that...

I still think nov0798 needs to go out and loosen the pulley on his car to 20-30 ft-lbs, and then let us know how things are after a few thousand miles Of course he won't do that because he knows what will happen and all the pdf files from various universities won't change the outcome.

20FHK02

This can be true for the references you cited. But we are talking about ONE engine here: the MB M111 engine. Engine types 1, 2, 3, ..., 100 are designed to require a key to carry torque, but this doesn't mean that ALL engines must be designed to be this way, becaues there are some exceptions that aren't. It is the same ideology that fruits have seeds, but not all plants that have seeds are fruits.

Didn't tedypedy's post already show a working engine with a broken key?? If you're talking about endurance limit, all engines will fail eventually.

levelr123g

hmm , they are worried about the extra load placed on the keyway due to increased pulley size. if the bolt does the transfer of torque then why would they be worried about keyway stress?

http://www.nevo.biz/tech.html

mdp c230k

Easy, because the bolt was designed to handle the amount of force encountered by the stock size pulley. If you put an extra half inch on the diameter the new torque on the pulley will be greater because it is through a greater distance, simple physics.

x15jq

Ok after reading this huge thread I have to comment on the lawnmower part.

The reason tehre is a key is beacause say u hit a tree stump or something that jams the blade. The key is designed to shear so the engine crank doesnt simply stop. If it did u would have a destroyed lawn mower. It would bend the crank from the sudden stop.


Same principle for our cars. If somethings stops the pulley from moving, it wont lock the crank, if it did u would bend it.

Keys are just like insurance in case something happens. Its designed to shear before engine damage occurs.

DCXdynodog

I cut my own lawn, by God, so I can afford to own a Benz.
Even if isn't a *real* one

DCXdynodog

This is wrong, go back and reread Kleeman's post. He has it correct.

Aluminum may not be the best choice but a proper design does work- some racing engines use aluminum dampers (note it is still a damper and not just a hub ).

felix k

ASP, Kleeman, Evosport pulleys; intercooler.........

what's the best and/or cheapest combination for getting more hp on a 2001 c240???

Buellwinkle

As far as I know the only only reasonably priced performance mod for you car, short of an engine swap is the Evosport underdrive pulley kit. You can put on a Kleemann supercharger/intercooler but that's about $10,000 installed from what I understand. Forum member BrabusCclass has had both done so he can give you a first hand evaluation.

tedypedy

I still have that little peice of the key that sheared off in my room. Here's my question. since the car runs fine, I don't see any abnormalities can I just put the ASP pulley on without worrying or is it gunna cause sum problems? However, its not just the key that was demolished. A chunk of the crank came off, and there's a little groove on the stock pulley from this explosion of bs that's going on in there. How do i get the dealer to look in there and replace everything? Hard to assess the situation but I don't know why they'd put the key in there if it didnt serve a function. I have no idea how long i've been driving with no key and all of that but I've never encounterd an engine faiure or malfunction yet. I haven't driven my car for about a week, not since i found out about the key but on the way home if anything the car felt more responsive. (still have my E as a back up car) Anyways what do you guys think i should do?

Buellwinkle

Tedypedy, you are in a tough spot. The key is fairly long, over 2" and the part that can be seen externally is fairly small. If for some reason the rest of they works it's way out you will be in big trouble. The key is also what aligned the timing sprocket. I'll PM you with some advice I can't share on the forum.

levelr123g

just take it to mb and tell them that you heard a loud pop or something, ask them to check it out. or tell them the car was making a noise and when you opened the hood, you saw the pulley wobbling and so you tightened it up, but you want it towed because you are afraid to drive it. or somehting. you could always try the truth, it sometimes works and you dont have to worry about getting your stories messed up.